MR2 Timing Part II - I think Im Boned: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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Sept. 1, 2009 8:03 p.m. pinchvalve SuperDork

It is not 180 degrees out, but it was so badly out that I couldn't see the marks. After much trial and error, it is getting closer.

If I line up the dimples on the toothed wheel on the distributor like I am supposed to, the car will only start if I rotate the distributor clockwise as far as it will go. The car still stutters and stalls and runs like poo, and I can't advance the timing to where it belongs. It is too retarded, and I mean that both ways.

If I remove the bolts that hold the dizzy in, I can rotate it a little bit more and it gets better, so I pulled the dizzy, and turned the toothed wheel back one tooth and reinserted. The car runs much better and starts right up, but the timing is now too advanced. I can't retard it enough

So can I simply give up and run it as is? If the far left line on the pulley is TDC, and the middle is 10-degrees and the third is 16-degrees, I would say that it idles at about 25 degrees when all warmed up. Oil pressure is good, no warning lights, no check engine...
Sept. 1, 2009 8:44 p.m. Jensenman SuperDork

Something is fishy for sure. Here's the thing: if the engine likes where the dizzy is installed when it's 'wrong', then chances are that's really 'right' and something else is 'wrong'. I am not overly familiar with the MR2 motor other than the basics (inline 4 DOHC) so I can't offer much real help. But I will toss out some possibles:

The cam gears could be on the wrong cams, that would make for some timing oddness. That's possible with 907 Lotuses for instance, you should see all the crazy marks. I've seen engines with cams mistimed which cranked up and idled fine but the engine ran like crap when under load at higher RPM.

The outer ring of the balancer has moved on the inner part (if it's a two piece 'bonded' balancer, that's real common on Isuzu 4 bangers). A quick Google image search shows a two piece bonded balancer.

Again an Isuzu 2.3/2.6 thing for sure: distributor installation is done with the engine at TDC on #4, not #1. If done on #1, the engine runs like crap but the timing marks are perfect. Sure to make you rip your hair out. Is the 'Yota the same way? The dizzy sticks out of the head the same way, IIRC.

If you are using flywheel timing marks, are they for sure the right ones? Some Subies use a different set of 'unmarked' marks for timing. BTDT, that was embarassing.

I had a Ford Courier (Mazda motor) that had weird timing issues, it just wouldn't stay timed. Turned out the roll pin for the dizzy drive gear was sheared. That one was a real head scratcher, particularly since the ends of the pin were still nicely installed in the gear.

Another thought: just how far do you have to rotate the dizzy to get the car to run right? If it's about 90 degrees, your plug wires could be off 1 tower. I did that on a Spitfire many moons ago. The only difference was that I could get the marks to line up with a light but the dizzy was turned so far I couldn't get the tach cable installed.
Sept. 1, 2009 9:01 p.m. Tyler H Dork

Stupid question maybe....but are you jumping terminals T and E1 when you're looking at the timing?

If not, the ECU will be trying to control the timing.

If you install the distributor following these instructions, then the bottom end and distributor with be "right" and if it still won't run, then you're timing belt is off. You can look for the mark on the cam through the oil filler and verify that you're at least close, and not 360' out.

BGB

Another stupid question: Did you mess around with the rotor? Any chance it stripped/slipped?
Sept. 1, 2009 10:24 p.m. RobL Reader

After reading this, I'm willing to bet that your exhaust cam is one tooth off. It will run - even run good with the lobes spread more than stock until you rev the engine. Did you turn the engine a few times after you did the timing belt and verify that the cams/crank were correct?
Sept. 1, 2009 10:47 p.m. P71 SuperDork

One of the cams is not "in phase" with the rest of your setup. In other words either the intake or exhaust cam is 1 tooth off (if it's DOHC). If it's SOHC then you've got me. Little 4-cylinders run really, really funky with anything 1 tooth off.
Sept. 3, 2009 4:20 p.m. pinchvalve SuperDork

All great ideas. I confirmed and reconfirmed that the crank, belt and cams are in perfect alignment. But from the MR2OC board, here are some interesting thoughts that dovetail with what I am hearing here.

First, when I turn the engine over, I am rotating the crank clockwise. If I rotate it counter-clockwise, things don't line up the same since the slack on the belt is different. If this is the direction the engine rotates, then that would explain it. I think I read to turn it clockwise, but perhaps I am wrong. I will check it.

Second, I had to replace the crank pulley when I rebuilt the motor. Apparently the pulley from the 4AGE on a Corolla uses different timing marks than on an MR2. I know how to check and we shall see.

If neither works, I will try crying, pouting, and holding my breath until I force it to run right!
Sept. 3, 2009 4:42 p.m. Dr. Hess SuperDork

Find TDC on the motor with a pencil down the spark plug hole. Then see where your timing marks are. You didn't mention replacing the pulley.
Sept. 3, 2009 5:12 p.m. GUNDY Reader

In reply to Dr. Hess: Have you checked to see if the rubber in the pully has seperated to let the timing mark slip.
Sept. 3, 2009 5:18 p.m. RobL Reader

If it's a different pulley - your TDC mark on the pulley will not line up on the mark on the engine when the engine is actually at TDC. Easy check.

I just checked my MR2 and the engine rotates clockwise in the engine bay when looking at it from the passenger side.
Sept. 5, 2009 9:21 p.m. pinchvalve SuperDork

Thanks guys! I am not laboring this weekend, but Monday I should be able to sort it.

Hey, if you can look in an MR2, I have another question. The coolant filler neck assembly is attached to the side of the engine bay with 2 bolts. One bolt also secures a pair of black wires with a yellow stripe...a ground wire. The shorter wire goes to an electrical connection coming off the engine block. The other is longer and ends in a round connector with a hole in the center. This obviously is held down by another bolt somewhere. I can't remember where! Can someone trace it and see what it should connect to?